The presence of neighbors affects waving display frequency by Scopimera globosa (Decapoda, Ocypodidae)

Scopimera globosa, a small ocypodid crab, rhythmically raises and lowers its body and both chelae in a waving display when it is not interacting directly with another individual. To determine whether waving is a social signal and to deduce its possible function, we manipulated the sex and density of crabs in a field enclosure and recorded the waving frequency of males. Males with abundant female neighbors waved significantly more often than when the same males were caged with abundant male neighbors. Males caged with fewer neighbors of either sex seldom waved. Thus, males waved most in the presence of females, especially at high density, and least in the presence of other males, suggesting that waving may function in female acquisition. Received: August 18, 1998 / Accepted: October 2, 1999     

Effects of inbreeding on economic traits of channel catfish

Summary Inbred channel catfish (Ictalurus punctatus) were produced from two generations of full-sib matings to study the effect of inbreeding on reproduction, growth and survival. A randomly mated control line was propagated from the same base population to be used for the evaluation of the inbred fish. First generation inbred (I1) and control (C1) lines comprised five full-sib families each. Second generation inbred (I2) and control (C2) lines were produced by mating each male catfish from the I1 or C1 line to two females in sequence, one from the I1 and one from the C1 line. The design also produced two reciprocal outcross lines to be compared to their contemporary inbred and control lines. The coefficient of inbreeding for the inbred line increased from 0.25 in generation 1 to 0.375 in generation 2. The inbreeding coefficient was zero for all other lines. The resulting fish were performance tested in two locations, Tifton, Georgia and Auburn, Alabama and no genotype-environment interactions occurred. Results indicated that one generation of inbreeding increased number of days required for eggs to hatch by 21%, but did not significantly influence spawn weight or hatchability score. However, inbred females produced more eggs/kg body weight than control females. Two generations of full-sib mating in Georgia did not depress weight when expressed as a deviation to random controls but was depressed 13–16% when expressed as a deviation to half-sib out-crosses. Second generation inbreds produced in Alabama exhibited a 19% depression for growth rate when compared to either random or half-sib outcross controls. Survival rates at various age intervals was not decreased by inbreeding. The amount of inbreeding depression varied among families and between sexes.This study was supported by State and Hatch Funds allocated to the Georgia and Alabama Agricultural Experiment Stations     

Photic and nonphotic responses of the circadian clock in serotonin-deficient Pet-1 knockout mice

The neurotransmitter serotonin plays an important role in the regulation of the circadian clock. To gain further insight into the mechanisms by which serotonin regulates rhythmicity, the authors investigated photic and nonphotic effects on the circadian clock in Pet-1 knockout mice. In these mice, the serotonergic system suffers a developmental loss of 70% of serotonin neurons, with the remaining neurons being deficient in serotonergic function as well. Pet-1 knockout mice show significantly decreased phase delays of the circadian clock in response to light pulses in the early night; however, this difference was not reflected in a difference in the expression of Fos protein in the suprachiasmatic nucleus. There were no genotypic differences detected in the phase-shifting response to injection of the 5-HT_1A/7 (serotonin 1A and 7) agonist 8-OH-DPAT ((±)-8-hydroxy-2-(dipropylamino)tetralin hydrobromide); however, there were small but significant differences in the phase-shifting responses to cages between genotypes and sexes. Several different patterns of wheel-running activity were observed in knockout mice that differed from those in wild-type mice, suggesting that normal serotonergic function is necessary for the proper consolidation of nocturnal activity. Overall, these data are consistent with other pharmacological and genetic studies demonstrating a significant role for serotonin in circadian clock function.     

一株分离自网箱养殖区沉积物的硫氧化菌B1-1的鉴定及其硫氧化特性

【背景】海水网箱养殖是一种高密度、高投饵的人工养殖方式,其产生的硫化物污染严重影响了海水养殖业的经济效益及可持续发展。【目的】鉴定从网箱养殖区沉积物中分离得到的硫氧化菌B1-1并研究其硫氧化特性,为利用生物技术修复网箱养殖环境提供理论依据。【方法】通过形态观察、生理生化特征及16S rRNA基因序列分析对硫氧化菌B1-1进行鉴定;通过摇床培养对该菌株氧化硫代硫酸盐的最适培养条件(pH、温度、底物浓度、外加碳源、外加氮源、金属离子)进行研究。【结果】该菌株被鉴定为HalothiobacillushydrothermalisB1-1。菌株B1-1生物氧化硫代硫酸盐的最适pH为8.0,最适生长温度为30°C,最适底物浓度为5.0g/L;外加碳源对该菌株氧化能力无显著影响,外加铵盐(硫酸铵或草酸铵)可以将延滞期缩短至12 h,添加Mg~(2+)可以显著提高菌株的氧化能力,氧化率达100%。【结论】Halothiobacillus hydrothermalisB1-1耐盐性较强,对硫代硫酸盐氧化率高,可作为修复受硫化物污染网箱养殖环境的潜在菌株资源。     

笼底类型对肉仔鸡行为的影响及其与胸囊肿发生率的关系

为研究笼养肉仔鸡胸囊肿发生的行为学机制,观察比较3种盒式笼(笼底分别由铁丝网、塑料片和竹竿组成)中肉仔鸡从3至6周龄的行为,以及胸囊肿发生率的差异。结果表明6周龄时,肉仔鸡在3种笼底上的伏卧行为虽无显著差异,但在行为格局中其比例最高(均在70%以上),而站立、行走和晃动3种行为之和仅占10%左右;竹竿笼底上的肉仔鸡行走频次、晃动频次和比例均显著高于铁丝和塑料笼底上的(均P<0.05),而竹竿笼底上的肉仔鸡胸囊肿发生率显著低于铁丝笼底上的(P<0.05);随着周龄增长,铁丝笼中肉仔鸡行走和晃动频次均减少,伏卧时间延长,胸骨承受的重量增大,这增加了胸部与铁丝网笼底接触及摩擦的几率和时间。实验结果说明,笼养肉仔鸡行为格局趋向静态单一化(动态行为频次降低,静态行为比例占优势)与其胸囊肿发病率的变化相一致,提示两者存在某种内在联系。这验证了我们提出的假设,即依赖于笼底类型和周龄的肉仔鸡行为趋向静态性是胸囊肿形成的必经环节。     

海水网箱养殖对环境的影响

综述了近20年来国内外关于网箱养殖对环境影响的研究动态和成果,包括网箱养殖碳、氮、磷和悬浮物输出造成水体的污染及对沉积物的影响、养殖过程中使用化学药品的污染、养殖鱼类逃逸对渔场生态环境的影响以及外来种、定向育种生物甚至转基因生物养殖所造成的基因污染,以及导致了养殖海区各类生物多样性的改变等,并对海水网箱养殖的可持续发展提出了一些看法和建议。     

Experimental trophic ecology of juvenile largemouth bass,Micropterus salmoides,and blue tilapia,Oreochromis aureus

Synopsis The potential for feeding competition between largemouth bass, Micropterus salmoides, and blue tilapia, Oreochromis areus, in Lake Fairfield, Texas was evaluated experimentally. Largemouth bass and blue tilapia were grown in cages alone and in combination with each other. The fish were allowed to feed on the natural food within the lake. Largemouth bass grown in combination with blue tilapia were significantly shorter and weighed less than largemouth bass grown alone. Blue tilapia grown in combination with largemouth bass were statistically significantly longer and heavier than blue tilapia grown alone. Largemouth bass grown alone had diets (volume and number of food items) significantly different than the largemouth bass grown with the blue tilapia. Largemouth bass fed primarily on chironomid larvae and pupae, and odonates, whereas blue tilapia consumed vegetable matter, detritus, and chironomid larvae. Length and weight differences between large-mouth bass grown alone and in combination with blue tilapia, in conjunction with the largemouth bass diet shift, support the theory that these two species compete for food resources.     

Reproductive performance,growth, and survival of selected and wild X selected channel catfish

Summary Wild (W) and selected (S) strains of channel catfish (Ictalurus punctatus) were crossed to attempt to introduce genes from wild stocks into a domesticated stock without loss of growth or survival performance. W strain broodfish were from the Kaskaskia River in Illinois and had no history of artificial selection. The S strain broodfish had undergone two generations of selection for multiple-traits since 1974 and had become adjusted to tank, cage, and pond culture conditions. Females and males from both strains were paired in individual spawning pens in all possible combinations and the 19 subsequent egg masses were artificially incubated. The 15 SXS, 6 WXS and 9SxW crosses produced 10, 3 and 6 egg masses, respectively. None of the 7 WXW pairs spawned. The fish density was standardized to two tanks of 500 in each full-sib family at 4 weeks of age and 200 in each at 12 weeks of age. Domesticated and crossbred fish did not differ in spawn characteristics or 4-week body weight but domesticated catfish grew progressively faster than crossbreds and were 55% heavier and 16% longer by 40 weeks of age. No survival differences were observed among the three genetic groups. A 9-week cage test which followed the tank culture also indicated that domesticated fish were superior to crossbreds in body weight, total length, condition factor, and carcass weight. These results indicated that a single WxS cross did not establish improved gene combinations without loss of growth performance.     

t-[35S]Butylbicyclophosphorothionate Binding Sites in Invertebrate Tissues

Specific high affinity binding of the cage convulsant t-[35S]butylbicyclophosphorothionate (TBPS) was observed in membrane homogenates of housefly heads and crayfish abdominal muscles. [35S]TBPS binding in these two invertebrate tissues was inhibited by biologically active cage convulsants, picrotoxin analogs, and barbiturates. The housefly binding sites were inhibited most potently by several insecticides. Approximately 50% of total binding was displaceable by excess (0.1 mM) nonradioactive TBPS, picrotoxinin, ethyl bicyclophosphate, or dieldrin. Optimal binding assay conditions for housefly homogenates included pH 7.5, 22 degrees C temperature, 0.3 M chloride concentration, and incubation for 60 min; for crayfish homogenates, 4 degrees C temperature and 150-min incubations were optimal. Scatchard plots of equilibrium binding indicated one site in both tissues (KD = 50 nM, Bmax = 250 fmol/mg protein in housefly; KD = 25 nM, Bmax = 100 fmol/mg protein in crayfish). Association kinetics in housefly were consistent with one rate constant (k+1 = 8 X 10(6) M-1 min-1), but dissociation was described better by two rate constants (k-1 = 0.28 min-1 and 0.042 min-1; calculated KD values of 80 nM and 12 nM). Displacement by cage convulsants showed Hill numbers near 0.5, also consistent with two populations of affinity, while displacement by other drugs showed Hill numbers near 1.0. [35S]TBPS binding in insects was most potently inhibited by the insecticides dieldrin (IC50 = 50 nM), aldrin, and lindane (200 nM), in a stereospecific manner, consistent with this binding site being the receptor for biological toxicity. [35S]TBPS binding was also inhibited by relatively high concentrations of some pyrethroid insecticides, such as deltamethrin and cypermethrin (1-2 microM).(ABSTRACT TRUNCATED AT 250 WORDS)     

Consequences of competition on the reproduction and mortality of three species of terrestrial slugs

The interaction of three species of terrestrial slugs was studied in six field cages containing monocultures and 2-way combinations. A. columbianus and A. ater were non-aggressive species and L. maximus was highly aggressive during the summer. All three species were similar in body design and resource utilization. Reproduction (egg size, eggs/batch, number of batches, wet-weight productivity) and mortality were monitored through the 1977 season. L. maximus drastically reduced reproductive success of the non-aggressive slugs and increased their mortality. There were also significant interactions between the non-aggressive species. Compared to other invertebrates, the life history characteristics of A. columbianus are strongly K-selected and probably evolved through intraspecific exploitative competition in predictable, stable forest habitats. A. ater is best classified as a refuging r-selected species adapted to less predictable, unstable field environments. L. maximus appears to be α-selected and its overall design is suited to density-dependent regulation in fields.